Longitudinal strip edge butt welding



Dec. 2, 1969 5 BRlGGs m Re. 26,726

LONGITUDINAL STRIP EDGE BUTT WELDING Original Filed Nov. 27, 1965 2Sheets-Sheet 1 FIG. 8

TO HIGH FREQUENCY CURRENT GENERATOR 8 CONTROLS INVENTOR. SIDNEY BRIGGSJEBY ATTORNEY Dec. 2, 1 s. BRIGGS m 26,726

LONGITUDINAL STRIP EDGE BUTT WELDING Original Filed Nov. 2?, 1963 2Sheets-Sheet z FlG. 5A

l6 l2 l8 FIG. 5B

FIG. 6

{I6 {49 L I I INVENTOR. min/7177 1 "ring/T SIDNEY BR|GGS,DI

\ BY W F1 6, 7 ATTORNEY United States Patent 26,726 LONGITUDINAL STRIPEDGE BUTT WELDING Sidney Briggs Ill, Bay City, Mich., assignor to TheThomson Corporation, Bay City, Mich., a corporation of Delaware OriginalNo. 3,325,623, dated June 13, 1967, Ser. No. 326,545, Nov. 27, 1963.Application for reissue Feb. 19, 1968, Ser. No. 728,096

Int. Cl. 323k 9/02, 11/02, 11/04 US. Cl. 219-102 21 Claims Matterenclosed in heavy brackets appears in the original patent but forms nopart of this reissue specification; matter printed in italics indicatesthe additions made by reissue.

This invention relates to longitudinal metal strip edge butt welding andmore particularly to apparatus for and a successful method of continuouswelding coil strip metals at adjacent longitudinal edges by highfrequency electrical currents.

The invention involves bringing metal strips into edgewise contact underpressure after heating such edges to plastic forging temperature by theapplication of edge heating high frequency currents. The edges to bewelded are substantially disposed in a common vertical plane butseparated from each other from a point at which welding of the stripsoccurs. In one embodiment of the invention, the adjacent longitudinalstrip edges are disposed at a vertical angle to each other but lie in aplane such that as the two strips are welded and drawn away from theirweld point no distortion of either of the strips is generated throughthe mechanical efforts applied by the apparatus.

In effecting a continuous running weld of the strips (taken from coils)at their adjacent edges, one of the strips enters the welding area ofthe apparatus at a substantially horizontal plane and leaves the areabutt welded to its complementary strip in substantially the same plane.The second strip enters the welding area from an elevated position andat an acute angle to the first strip, the planes of the two stripsintersecting in a line substantially at or closely adjacent the weldingpoint of the strips. Inasmuch as the two strip planes are intersected bya transverse plane containing the longitudinal edges to be welded, themore nearly the transverse plane is normal to the strip planes the moreeffective and efficient will be the welding of the two strips.

A theoretically perfect vertical alignment of the edges would not,however, provide a successful weld. If the adjacent strip edges wouldjust pass each other or would just brush against each other as they comeinto planar alignment, it would be necessary to compress the strips intheir welding plane to a degree or magnitude such that planar distortionforward of the weld or forging point would naturally result. In suchevent, the meeting edges would be put into tension and the remote edgesinto compression, the planar distortion interfering with a successfulcontinuous production weld.

A practical successful solution to the strip butt edge welding problemhas been found in the discovery that by a very slight overhang of thehigher strip with respect to the inner edge of the lower strip, anoverhang measured in a few thousandths of an inch, the two strips can bebutt welded together by lateral forging rolls and vertical compressionrolls on a continuous production basis by the apparatus and the methoddescribed below. It has further been found that by disposing the forgingplane (i.e. a vertical plane passed through the vertical axes of theforging rolls) just slightly forward of the vertical compression plane(i.e. the plane through the horizontal axes of the compression rolls)more accurate and positive control over the weld point is achieved.

This control over the weld point is significant and important. Highfrequency electric currents, generated by Reissued Dec. 2, 1969 a radiofrequency generator capable of an output of 60 or more kilowatts ofcurrent at from to 450 kilocycles, are utilized to heat the edge surfaceof each of the metal strips that will be compressed together by theforging rolls. In order to heat these edges by high frequency current, agenerator of suitable capacity and frequency together with controls isinstalled adjacent the strip welding apparatus, and current conductorsare extended from the generator and auxiliary equipment, if any, toelectrodes making contact with the strips to be welded. The electrodes,one on each strip, are disposed at a short distance from the plane ofthe forging rolls passing transversely through the strips adjacent theweld point. The currents produced by the generator at high frequencytravel substantially on the surface of the strips from and between thecontact points of the electrodes to the weld point. As the conductingmetal surfaces heat up under the excitation of the alternating currentflow, the edge surfaces appear to become heated to plastic temperaturein the range for cold rolled and stainless steels of from approximately2000 F. to approximately 2400 F.

The temperatures reached by the edge surfaces are dependent in a measureupon the distances of the electrodes to the Weld point. If the weldpoint varies or flunctuates, the temperature at the edge surfaces risesand falls in direct proportion, i.e. if the weld point distance from theelectrode contact increases, the temperature increases, and if the weldpoint distance decreases, the temperature drops. Under these conditions,control of the weld point becomes a most desirable if not a necessaryand essential factor in the process. It has been found that by disposingthe plane through the strip forging rolls just slightly ahead of theplane through the horizontal pinch rolls the weld point shift is moreclosely confined and limited than when the two planes coincide. Thus, asignificant variable has been reduced to a closely controlled factorwhereby edge temperatures are relatively stable and controllable.

Heat depth penetration in the metal strip edges is another factor to beconsidered in the continuous butt welding process and is provided for inthe apparatus of this invention. The heat depth penetration increases asthe temperature of the edge increases. Only slight heat penetration isdesirable inasmuch as the forging pressures applied are substantial, andexcessive forging at the butt-weld edges will result in substantial andundesirable upset of the weld metal. Therefore, the flow rate of metal,the power and frequency of current applied at the electrodes, thedistances of the electrodes to the weld point, the relatively constantposition of the weld point, and the slight overhang relationship of thestrip edges being heated to plasticity are all factors that requirecooperation and coordination to produce a successful method andapparatus for butt welding the longitudinal adjacent edges of metalstrip in a continuous production manner. These factors have beenstabilized and controlled in the apparatus and by the method of thisinvention.

It is an object of the invention to provide apparatus and process forbutt welding the surfaces of adjacent longitudinal edges of metal stripby means of high frequency electric currents applied to and heating suchedge surfaces. Another object is to provide means for closelycontrolling the weld point in the path of such electric currents bymeans of forging and compression roll location and orientation. Afurther object is to provide apparatus for moving the metal strips intothe welding area in such a manner that when the edges to be welded arebrought into butt welding relationship there is a slight overhang of theedge portions heated to plasticity so that these portions engage andwipe across each other as they pass through the weld zone and are forgedtogether by laterally applied forging rolls at or adjacent the weldpoint, rather than being substantially lapped horizontally andcompressed vertically, as in the forming of a lap seam or joint. Anotherobject is to provide horizontal pinch rolls upon the composite weldedmetal strip at a point or line just a little beyond the line ofapplication of the forging pressure. A further object is to coordinatethe temperature of the electrically heated zones at the edges to be buttwelded with the flow rate of the metal strips for controlling thelocation of the weld point within relatively close limits. A principalobject is to provide apparatus and process for successfully butt weldinglongitudinal adjacent edges of metal strip in a continuous productionmanner by the application of high frequency electric current to suchedges.

These and additional objects of the invention and features ofconstruction and processing will become more clearly apparent from thedescription given below in which the terms employed are used forpurposes of description and not of limitation.

Reference is here made to the drawings annexed hereto and forming anintegral part of this specification, and in which FIGURE 1 is aperspective view of one embodiment of apparatus for practicing theinvention in connection with the butt welding of metal strips.

FIGURE 2 is a vertical elevational view partially in section [sectional]taken substantially on the line 2-2 of FIGURE 1.

FIGURE 3 is a slightly enlarged fragmentary perspective view taken froma point just forward of the weld point and the forging rolls.

FIGURE 4 is a fragmentary perspective view show ing a gas hood over thewelding zone, the forging rolls and the horizontal compression rolls.

FIGURE 5A is a vertical sectional view taken transversely of the twometal strips as they approach the weld point beyond the electrodes.

FIGURE 5B is a vertical sectional view, similar to that in FIGURE 5A,showing what is believed to occur as the two adjacent strip edges,heated to plasticity, slip and wipe across each other.

FIGURE 6 is an enlarged fragmentary transverse vertical sectional viewtaken at the welded zone of the composite strip.

FIGURE 7 is a fragmentary top plan view of the composite strip.

FIGURE 8 is a vertical view, substantially in elevation takensubstantially on the line 8-8 of FIGURE 1.

As shown in the several views of the drawings, the apparatus 10 for buttwelding adjacent longitudinal edges 12 and 14 of metal strips 16 and 18,respectively, comprises a fixture base 20, strip guide rolls 22 onstands 24, strip tensioning rolls 26, an electrode contact weldingfixture 28, strip supports 30, 32 under the fixture, horizontally actingstrip forging rolls 34, 36 supported in fixtures 38, 40 respectively andheld in compression against the outer lateral edges of the two strips bya pneumatic air cylinder 42, the fixtures 38, 40 and the cylinder 42being supported on an auxiliary base 44, vertically acting compressionrolls 46, 48 operating on the welded composite strip to draw it toward awind-up reel (not shown) from the compression rolls. The high frequencygenerator supplying the current and power for the welding operation isnot shown, nor are several other units including a current transformer,and manually operable control devices, all well known by persons skilledin the art to which the invention pertains.

The metal strips 16 and 18 are electrically conductive in nature andmore particularly, but not exclusively, are principally ferrous incomposition. The strips may be relatively thin or thick incross-section. Successful butt welding by the apparatus and methodhereindisclosed has been practiced upon strips of from .018 to .028 inchinclusive, but strip thickness of greater or lesser magnitude can alsobe successively butt welded by the instant apparatus and method. some ofthe strips that have been butt welded together are electrogalvanized(zinc coated) cold rolled steel and stainless steel. Ordinary coldrolled steel and other steels have also been successfully butt weldedtogether into edge-fused strips. [composite strips. The term "compositestrip includes welded identical strip materials as well as diverse stripmaterials] The two strips are taken from reel supported coils (notshown) mounted on stands insulated from each other and from the fioor orbase upon which the reels or mounts are supported. Electrical currentsintroduced by the generator and controls to the two strips by thecontact fixture 28 will flow in the directions of least impedance andreactance and generally through a circuit toward each contact or to aground. In order to limit current losses and undesired metal heating,the fixture elements making direct contact with the metal strips arepreferably insulated from each other and from the base or mounts uponwhich they are supported. This requirement is particularly applicable tothe stands 24, tensioning rolls 26, forging roll fixtures 38, 40 and thecompression rolls, 46, 48.

The fixture base 20 is preferably supported on a rigid base or stand soas to elevate the welding fixture 28 to a level about waist high, orslightly higher, for more effective observation of the strips passingthrough the fixture by an operator handling the power generatorcontrols. Mounted on the base 20 are the strip guide roll stands 24having at least four (4) guide rolls 22 adjustably secured to the standso that strip 18 is positively guided into position laterally adjacentthe complementary strip 16 at the weld zone, as in FIGURE 3. Alignmentof the strips 16 and 18 starting from the coil and reel positions iscritical and care must be exercised in respect to such alignment inorder to produce a successful continuous production weld of the strips.The strip 16 is similarly guided by its stand 24 supported on base 20but elevated by support 30 so that the strip 16 enters the weld zone atan acute angle to the plane of the strip 18.

Under each of the guide roll stands 24 are insulating sheets or pads 56required to electrically insulate the stands and their strips from eachother. Guide rollers 22 are adjustable laterally of the stands 24 sothat the strips 16 and 18 will line up in a very slightly overhangingrelationship. This overhang disposition or attitude is maintained fromthe initial coil position, and is carried through guide roll stands 24and the strip supports 30, 32. By so doing, the strips come into weldattitude in a true flat overhung disposition as shown in FIGURE 5A.

The overhang of strip 16 with respect to strip 18 is measured in a fewthousandths of an inch. Coil strip stock is produced and sold in widthshaving variable tolerances. To hold the composite strip width withinlimits such that the upset at the weld line is relatively small andcontrollable, the width of the composite strip is established at fromabout .005 to about .010 inch less than the combined widths of the twostrips being welded. The selection and determination of the widthdiminishing factor is based in part upon the compression force of thecompressive [compression] rolls 46, 48 operating against the upset beadand upon the variation in tolerances of the two strips. The nominalforging reduction of the rolls 34, 36 for strips of approximately .020inch thickness is about .008 inch, providing an upset head at the weldline that is easily compressed by the compression rolls 46, 48 toproduce a [composite strip] welded strip length 49 of substantiallyuniform thickness throughout.

As the strips 16-, 18 leave their guide roll stands, a pair of pinch ordrag rolls 26, 26 apply a braking action upon the strips. These rollsare mounted in stands (not shown) in such a manner that the strips aresubjected to considerable pressure by and between the rolls, which aremade of a polyurethane plastic composition known by the trade nameDisogrin. However, other materials similar in function can also beutilized. The pressure applied by the rolls 26, 26 is such that thestrips are dragged and gripped by the rolls with great frictionalengagement, thus eliecting a braking or tensioning action upon them fromthe rolls 26, 26 through to the draw rolls 50, 52. Holding the stripsunder firm tension in the weld zone eliminates buckling or flexing ofthe strips and consequently improves control of the overhangingrelationship of the strip edges 12 and 14, and of the weld point.

Upon leaving rolls 26, 26, strip 18 moves to a slide position upon thesupport 32 which comprises a base 60, a post 62, and a strip rest 64secured to the post which is adjustable vertically in base 60. The rest64 is rotatably adjustable in a vertical plane on a pin 66 mounted inthe post, the adjusted position being secured by a screw 68 passedthrough a semi-circular slot in the rest plate 70. The rest 64 of stripsupport 32 is disposed in a substantially horizontal plane for strip 18.The strip support 30 is composed of the same elements as those describedfor support 32, the rest 64 being disposed at an acute angle to thehorizontal to accommodate the strip 16. For the strips heretofore testedand welded, the rest 64 of strip support 30 is disposed at an acuteangle to the horizontal plane ranging from 3 to as a preferred angularrange. However, for other strip Welding such angular relationship can bemodified by increasing or decreasing the angle depending upon thecriticality of the power input at the electrode contacts, the speed orflow rate of the two strips, the proximity of the currentcarrying edgeportions, the relative shift or non-shift of the weld point, and thepresence of arcing across the strips in the area of the current-carryingedge portions. Since the electrical efiiciency of the high frequencycircuit between electrode contacts and through the weld point isincreased as the angular relationship of the current paths approachzero, the optimum angular relationship of the two strips is reached whenfor a given power input at a particular frequency and at a given stripfiow rate, the angle between the strips is just slightly greater thanthat angle at which arcing between the electrodes or the strips has orwill occur.

Disposed above the strips 16 and 18 at the supports 30 and 32,respectively, is the electrode mount 28. This mount can be constructedin a number of Ways, and such constructions form no direct part of theinstant invention. A representative embodiment of a mount that can beutilized comprises an electrode contact 80 secured to an arm 82pivotable about a pin 84, the arm being held against a resilient spring86 so that the contact 80 is freely s'lidable and in electrical andbearing contact with and upon the strip at all times, the upper end 88of the mount being securely held in supports (not shown) cooperativelyassociated with the current generator equipment. Each side of the mountis insulated from the other side and is direct connected to thegenerator equipment by an individual liquid cooled current conductor 90.

The electrode contacts 80 ride the strips 16-, 18 adjacent the edges 12and 14, respectively, welding current flowing upon the surfaces of thestrips adjacent these edges and heating them as the metal resists thehigh frequency flow and reverse flow of the current. Having in mind thatthe strips are moving at a very high speed past the electrode contacts80, where Welding current is imparted to the strips, the time period ofcurrent acceptance is only a small fraction of a second. Yet within thatperiod, the surfaces of the edges are heated'to a temperature at whichthe metal is plastic and the edges weldable. As a representative exampleonly, and without limitation against modification for other situations,electrogalvanized cold rolled steel strip has been butt welded tostainless steel strip in a continuous production manner at a speed orflow rate of 400 feet per minute or more, the electrode contacts 80being disposed at a distance of approximately 3 inches from the weldpoint on the galvanized steel strip and at about 2 inches on thestainless steel strip, using a 60 kw. generator operating at a frequencyof 450 kilocycles. Under these conditions the galvanized steel stripedge is being heated to welding temperature in about .0375 second andthe stainless steel strip edge in about .025 second.

It has been found that in welding zinc coated galvanized steel strip tostainless steel strip, some of the zinc in the surface area heated bythe electric currents becomes vaporized and oxidized and surrounds theweld zone in a cloud of zinc ions or zinc oxide particles that tend toshort out the currents and reduce their welding effectiveness. Toeliminate this defect where a zinc surface coating is present on thestrip, a neutral or inert gas such as carbon dioxide has been introducedwithin a hood 96 by means of a conduit 98 leading from a source ofsupply of such gas (FIG. 4). Nitrogen or other inert gas may be appliedwithin the hood or by jets to clear away the zinc. The hood is disposedover the area of the weld zone and is open wherever mechanical parts orother structural features are present. The gas is continuously fed ormetered into the hood and escapes to the atmosphere from areas ofmachine components adjacent edges of the hood. The carbon dioxide gasreduces the oxidation of the zinc, thereby eliminating arcing or shortcircuiting of the currents during the heating and welding operation.

As seen in FIGS. 1, 3 and 8, the compression rolls 46, 48 are verticallyarranged above the [composite strip] welded strip 49, and are disposedslightly rearwardly of the forging rolls 34, 36, i.e., a vertical planepassed through the horizontal axes of the compression rolls is just abit rearwardly of a vertical plane passed through the axes of thehorizontal forging rolls. It was found that setting the compressionrolls in vertical alignment with the forging rolls interfered witheffective butt welding of the strips. When the compression rolls wereplaced slightly behind the forging rolls, the latter were able to actmore effectively upon the weld point and to weld the [composite strip]welded strip. By allowing only one set of rolls, the forging rolls, tooperate upon the two strips at the weld zone, it was further found thatthe weld point was more successfully controlled and limited in itslongitudinal shift, than if both sets of rolls were in operationsimultaneously upon the strips.

The compression rolls 46, 48 are held in pressure bearing contact uponthe welded strip [composite strip] 49 by the compression springs 100operating on posts 102 against the shaft supports 104, 104 to compressthe upset bead of the [welded composite] strip 49. The pressure appliedby the springs can be increased or decreased by adjusting the springretaining caps 106 downwards or upwards. When both strips 16 and 18 areof equal thickness, the rolls 46, 48 are uniformly ground. Should a[composite strip] product be required or produced of two strips ofunequal thickness, the rolls 46, 48 should be machined and ground toaccommodate the configuration at the Weld line, having in mind thecompression of upset metal. This is the essential action of rolls 46,48, Le, it is not an action of vertically compressing or mashing alapped joint, as in known seam welders.

After passing through the compression rolls 46, 48, the welded strip[composite strip] 49 is drawn by the rolls 50, 52, which may be singlestand or multiple stand as required, to the wind-up reel (not shown)that can be at a fair distance from the rolls 50, 52. Time should beallowed for the welded metal to cool sutficiently for generation andstabilization of the desired metallurgical structure before subjectingthe [composite strip] finished strip to mechanical working by bendingabout the windup reel.

The very slight overhang of the two strips 16, 18 as they approach theweld point (FIGURES 2 and 3) is so controlled that the heated edges 12and 14, as shown in FIG- URES 5A, 5B and 6, tend to wipe across eachother,

and become no longer overlapped. It is believed that, due to the heatgenerated in the edges and particularly to the concentration of heat inthe surfaces of closely adjacent and approaching edge portions, themetal at one edge is wiped across the metal of the adjacent edgeproducing, under pressure of the forging rolls, a forged welded juncture110 as shown in FIGURE 6 just prior to upset compression by the[compression] compressive rolls 46, 48. Inasmuch as the speed of thewelding operation is at the rate of 80 inches or more of strip persecond, it is not as yet possible to fully and accurately determineexactly what takes place in the edge wiping area of the weld zone, butit is believed that the above constitutes a very possible and probabledescription of the operation.

Such a weld method is not a lap or mash weld of the two strips, butappears to be a true butt weld process in that the edges are insubstantially planar contact when the forging rolls 34, 36 apply theirhorizontal pressure. Under such pressure, it would appear that the heatsink in each of the metal edges 12 and 14 is increased to a slightlygreater depth so that a more uniform and more satisfactory weldstructure is achieved than would occur with a lap or mash weld.

Forging pressure applied by the rolls 34, 36 is controlled by thepneumatic air cylinder 42 operating through the rod 112 and roll support114. The set screw 116 predetermines the width of the [composite strip]finished strip 49 and the allowable forward movement of the roll 36.

The forging rolls 34, 36 are preferably made of bronze, brass or othernonmagnetic materials such as ceramics. It appears that, due to theclose proximity of the rolls to the welding current paths, rolls ofsteel become inductively heated to temperatures at which they cannotoperate with efficiency. Lubrication in the bearings of such steel rollsis liquified and runs out so that the rolls rotate on dry shafts andseize at their bearings. The forging rolls operate under an appliedpressure from the air cyclinder 42, further adding to the load on thebearings. To avoid such failure, the rolls 34, 36 and their bearings aretherefore made of the aforementioned nonmagnetic materials which are notsubject to induction heating.

Although actual testing resulting in the [composite strip] welded stripformed by the method and apparatus of this invention has been made witha high frequency generator operating at about 450,000 cycles per second,it is to be understood that high frequency equipment operating atfrequencies of the order of from about 100,000 cycles per second up toand even beyond the range of 450,000 cycles per second can be utilizedin the method and in connection with the apparatus of this invention.Where thin strip materials are being welded, the higher frequencies arepreferred in order to obtain suitable surface welding temperatures witha minimum of heat depth penetration. For metal strips of relativelygreater thickness the frequency range could be lower than 450,000 cyclesper second in order to achieve a slightly greater heat depth penetrationat the edges to be welded.

The overhanging and overhung relationship of the two strips 16 and 18from positions adjacent their coils or from the positions of the dragrolls 26, 26 through to the draw rolls 50, 52 is of course somewhatcritical. The wiping action of the heated edges desired in theprocessing of the welded strip [composite strip] will be effected ifsuch overhang is less that which results in a lap at the welded edges. Alap weld requiring a mashing of the lap, does not come within the scopeor concept of this invention which involves only a butt welding of theheated edges. Although some upset material is generated in the wipingaction of the edges, no lap nor overlying weld of the two strips resultsfrom the overhanging relationship of one strip with respect to the otherin the weld zone of this processing and apparatus. The forging rolls 34,36

compress the strips 16 and 18 together into a butt weld, throwing up aslight upset from each strip, in the plane assumed by the strips justprior to their entry between the [compression] compressive rolls 46, 48.See FIGS. 5A, 5B and 6.

For relatively light gauge strip stock, an overhangingoverhung magnitudeof from just over the edge of onestrip to approximately one-half thethickness of the strip Which is being overhung would appear to besatisfactory in the process of this invention for the production of anacceptable butt weld seam and [composite strip] union. Such gages wouldbe in the thickness range of from .010" to .060" inclusive. For heavierstrip stock, the overhanging-overhung magnitude could be up to as muchas the full thickness of the strip which is being overhung.

The inventive method of high frequency electric current welding of dualcomponent [composite strip] hereindisclosed comprises disposing twometal strips [in planes] at an acute angle to each other such that theadjacent interior edge of one strip just slightly overhangs the adjacentinterior edge of the second strip as they are drawn toward a weld point,introducing and conducting such current to the strips at their adjacentedges, wiping the interior adjacent edges now heated to a welding stateby such current across each other into butt relationship, and forgingthem together by laterally disposed rolls applied under pressure to theexterior edges of the strips just prior to the compression of thecomposite strip between rolls operating upon the now-welded strip.Neither the forging rolls nor the [compression] compressive rolls aredraw rolls, these being applied beyond the site of the [compression]rolls and after welding of the strips into a [composite strip] finishedstrip has been completed.

In the process of the invention the two strips are aligned with respectto each other so that their interior edges are maintained insubstantially the same parallel lines from the coil reels through theguide roll stands 24, the drag rolls 26, 26, and the strip supports 64to the weld point, with a minimum of distortion and misalignment.

The apparatus described herein represents one embodiment of structureswhich can utilize the concept of invention hereindisclosed. Suchapparatus provides guide roll stands that positively line up theinterior strip edges 12 and 14 in a slightly overhanging relationship,supports that maintain the entry angle of the strips 16 and .18 of anorder such that arcing is eliminated while maintaining currentefficiencies at optimum or near-optimum values, and that provideslaterally operating forging rolls to forge weld the strips together at aline ahead of [compression] compressive rolls which compress the weldupset bead and the [composite] final welded strip to a uniform thicknesswhile maintaining the weld point substantially at a single position withrespect to the fixed electrode contacts.

Having described the invention in its simplest terms, it is to beunderstood that the features of the process and apparatushereindisclosed may be changed and somewhat varied in degree withoutdeparting from the essence of the invention.

1 claim:

1. In the method for continuous production welding of a seam extendingalong adjacent edges of elongated metal strips, continuously advancingportions of said strips with their said adjacent edges toward and intothe line of the desired seam and through and past a weld zone containinga weld point, introducing and conducting an electrical current from asource to said metal strips by two terminals in respective electricalcontact with said strips so as to heat said edges by said current to awelding state, said terminals initiating said weld zone in said stripsat positions where said strips are in a substantially spaced apartattitude and substantially in advance of said weld point, advancing oneof said strips substantially along a plane disposed at an acute angle tothe plane along which the second strip is being advanced into said weldzone toward said weld point, and disposing and maintaining said adjacentedges at least in said weld zone in a slightly overhanging and overhungrelationship, while restraining said adjacent edges from lateralseparation parallel to said plane from said relationship by exertingrestraining effort on the strips in said weld zone and in lateraldirections toward said adjacent edges, so as to cause said heated edgesto wipe across each other as they approach and pass into said weld pointand become welded in a common plane.

2. The method of claim 1, in which said acute angle approximates 3 to10.

3. The method of claim 1, and further comprising placing said strips intension between points substantially ahead of the strip contactpositions of said terminals and a point beyond the position at whichsaid strips are welded in a common plane.

4. ln apparatus for welding a seam extending along adjacent edges ofelongated metal strips, means for continuously drawing portions of saidstrips with their adjacent edges advancing toward and into the line ofthe desired seam, a source of electrical current, terminals connected tosaid source of current and disposed in electrical contact with each ofsaid metal strips respectively to introduce said current to said metalstrips adjacent said edges and form a weld zone from said terminals to aweld point, means for disposing one of said strips in a plane andanother of said strips in a second plane at an acute angle to said firstplane, and means to dispose and maintain said adjacent edges at least insaid weld zone in a slightly overhanging-overhung relationship from saidterminals to a position adjacent said weld point said last named meanscomprising means exerting restraining effort on the strips in saidwelded zone and in lateral directions toward said adjacent edges, so asto prevent lateral separation thereof and so as to bring said adjacentedges when heated to a welding state into edge wiping relationship insaid weld zone as they approach and pass into said weld point and becomewelded in a common plane.

5. The apparatus of claim 4, in which the angle at which said firstnamed disposing means positions said strips approximates 3 to 10.

6. The apparatus of claim 4, and further comprising means to place saidstrips in tension between points substantially ahead of the stripcontact positions of said terminals and a position beyond the point atwhich said strips are welded in a common plane.

7. The apparatus of claim 6, in which said strip tensioning meanscomprises a pair of rollers engaging each of said strips substantiallyahead of the strip contact positions of said terminals and applying abraking action upon each strip.

8. The apparatus of claim 6, in which said strip tensioning meanscomprises a pair of rollers engaging each of said strips substantiallyahead of the strip contact positions of said terminals and applying abraking action upon each strip, and means engaging opposite edges ofeach strip in advance of said strip contact positions to confine thesame laterally in approaching said welded zone.

9. A method for continuous production welding of a seam extending alongadjacent edges of elongated metal strips, comprising continuouslyadvancing portions of said strips with their said adjacent edges towardand into the line of the desired seam and through and past a weld zonecontaining a weld point, intensely heating said edges to a welding stateat positions where said strips are in a substantially spaced apartattitude and substantialy in advance of said weld point, advancing oneof said strips substantially along a plane disposed at an acute angle tothe plane along which said second strip is being advanced into said weldzone toward said weld point, and disposing and maintaining said adjacentedges at least in said weld zone in a slightly overhanging and overhungrelationship, while restraining said adjacent edges from lateralseparation parallel to said plane from said relationship by exertingrestraining effort on the strips in said weld zone and in lateraldirections toward said adjacent edges, so as to cause said heated edgesto wipe across each other as they approach and pass into said weld pointand become welded [as a composite strip] in a common plane.

10. The method of claim 9, in which said strips are of similarlyrelatively light gauge stock, the dimension of said overhanging andoverhung relationship approximating one half the thickness of the stock.

11. The method of claim 9, in which the dimension of said overhangingand overhung relationship approximates the thickness of the stock of thestrips.

12. The method of claim 9, and further comprising placing said strips intension between points substantially ahead of said weld point and behindthe point at which the strips are welded in a common plane, andlaterally confining said strips against lateral separation inapproaching said weld zone.

13. A method for the continuous production w lding of a sedm extendingalong adjacent edges of elongated metal strips, comprising continuouslyadvancing portions of said strips and their said adjacent edges toward,through and past a weld zone containing a weld point, intensely heatingsaid edges to a welding state at positions where said strips are in asubstantially spaced-apart attitude in advance of said weld point,advancing said strips convergently toward one another and substantiallyat on acute angle to a line along which said strips pass said weldpoint, and disposing and maintaining said adjacent edges at least insaid weld zone in a slightly overhanging and overhung relationship, withsaid adjacent edges in a predetermined lateral relationship to saidline, so as to cause said heated edges to wipe across each other as theyapproach said weld point and become welded in a common plane.

14. A method for the continuous production welding of a seam extendingalong adjacent edges of elongated metal strips, comprising continuouslyadvancing portions of said strips and their said adjacent edges toward,through and past a weld zone containing a weld point, intensely heatingsaid edges to a welding state at positions where said strips are in asubstantially spaced-apart attitude in advance of said weld point,advancing said strips convergently toword one another and substantiallya! on acute angle to a line along which said strips pass said weldpoint, and disposing and maintaining said adjacent edges or least insaid weld zone in a slightly overhanging and overhung relationship, withsaid adjacent edges in a predetermined lateral relotionship to saidline, by laterally guiding at least one of the strips forwardly of saidweld point, so as to cause said heated edges to wipe across each otheras they approach said weld point and become welded in a common plane.

15. The method of claim 13, in which said welded strips are of differentmetals.

16. The method of claim 14, in which said strips are difierent metalsand of similarly relatively light gauge stock.

17. The method of claim 13, is which said strips are of dificrent metalsand of similarly relatively light gauge stock, the dimension of saidoverhanging and overhung relationship approximating one-half thethickness of the stock.

18. The method of claim 13, in which said strips are of difierent metalsand of similarly relatively light gauge stock, the dimension of saidoverhanging and overhung relationship approximating the thickness of thestock of the strips.

19. The method of claim 13, and further comprising placing said stripsin tension substantially ahead of said weld point.

20. The method of claim 14, and further comprising placing said stripsin tension substantially ahead of said weld point.

21. A method for the welding of a butt seam between adiacent edges ofmetal strips, comprising relatively moving said strips toward oneanother in a weld zone, intensely heating said edges to a welding statewhen said strips are in a spaced-apart relation to one another in saidweld zone, while maintaining said adjacent edges at least in said weldzone in a slightly overhanging and ov rhung lateral relationship andcausing said heated edges to wipe across each other transversely of thestrip surfaces to become welded in a common plane.

References Cited 12 2,647,981 8/1953 Wogerbauer 219-6 2,774,857 12/1956Rudd et a1. 219-67 2,821,619 1/1958 Rudd 219-107 2,857,503 10/1958 Ruddet a1. 219-59 2,886,691 5/1959 Rudd 219-67 2,922,020 1/1960 Andrew219-59 X 3,017,494 1/1962 Mackey 219-72 X 3,193,657 7/1965 Gebauer219-72 X 1,092,207 4/1914 Ryan 219-52 X 1,357,156 10/1920 Von Eckmann219-105 2,922,020 1/1960 Andrew 219-59 3,017,494 1/1962 Mackey 219-72 X3,193,657 7/1965 Gebauer 219-72 X JOSEPH V. TRUHE, Primary Examiner B.A. STEIN, Assistant Examiner U.S. Cl. X.R.

